Visit Our UNIX and Linux User Community


truncate file script is not working


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting truncate file script is not working
# 1  
Old 10-19-2007
truncate file script is not working

Hi All,
I have an application which writes log in to a file. The file size becomes around min of 800 MB a day. So I have written a script which backup the file and truncate the original file. My script is like this

cp X.log /backup/X.log1
> X.log

But the second truncate command is not working properly.The file is truncated to 0 byte but whenever the application writes the next log the file size is coming to the previous original size.

Can anyone please guide how to truncate the file properly.

Thanks in Advance
Venkat
# 2  
Old 10-22-2007
Try this

Code:
cp X.log /backup/X.log1
string X.log > X.log

Thanks,
Sam
# 3  
Old 10-22-2007
Quote:
Originally Posted by mvenkat_in
But the second truncate command is not working properly.The file is truncated to 0 byte but whenever the application writes the next log the file size is coming to the previous original size.
From what you are describing, the truncate command is working - setting to zero bytes. It's just that the application immediately rewrites it. The question is why does it start at the previous original size? Is that different than when the log is first created? If it is different, what data gets written to account for the extra space? Is the application somehow tracking where to write to log?
# 4  
Old 10-24-2007
Hi,
Your doubt is right. The application was opening the log file in the WRITE mode but not in APPEND mode. That is why even if I truncate the file, the application doesnt know about the change in the offset of the log file. So the application was writing the log after the next offset what it was previously but not from the starting.
I have changed the configurations so that the application opens the log file in APPEND mode and it is working now.

Thanks all.

Previous Thread | Next Thread
Test Your Knowledge in Computers #314
Difficulty: Easy
Pointers were not used in the original C programming language and were added later in in C++.
True or False?

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Script to truncate wtmp files

Hi, Does anyone have a script to truncate the wtmp file. I want to move older entries in the wtmp to a new file and move it out of var/adm and shrink the size. (4 Replies)
Discussion started by: ElizabethPJ
4 Replies

2. UNIX for Dummies Questions & Answers

recover the truncate file

hi All, how to recover the truncate file in unix. Thanks!:wall: (2 Replies)
Discussion started by: krbala1985
2 Replies

3. UNIX for Dummies Questions & Answers

Script required to truncate all the lines except a specific snippet.

Hi, I have a file with the following structure. XXXXX........... YYYYY........... ................. .................. ZZZZZZ...... qwerty_start.............. .................. ................. .................. querty_end................ .............................. (3 Replies)
Discussion started by: abinash
3 Replies

4. Shell Programming and Scripting

Truncate file name to 40 characters

Hello all. I would like to make a script (or two shell scripts) that will do the following. I need the maximum file name and directory name to be 38 characters long. As well, if shortening the file name ends up making all of the files in that directory have the same name, then I would like... (9 Replies)
Discussion started by: marcozd
9 Replies

5. Shell Programming and Scripting

Truncate extra contents from file

Hi all, i have a file and i want that after 6th slash "/" in each line of the file the contents gets truncated. Can anyone tell me how to do that !! thanks in advance One more thing how can i change the size of output buffer of console, as i had very long output and its not... (2 Replies)
Discussion started by: glamo_2312
2 Replies

6. Shell Programming and Scripting

Truncate multiple file extensions

Hi, I have files with names like file1.txt.txt.txt.txt and file2.txt.txt.txt.txt.txt............ (random infinite number of .txt exist). how to truncate (mv) their names to ones with single .txt extension like file1.txt and file1.txt ? In other words, how to extract the filename upto first... (12 Replies)
Discussion started by: prvnrk
12 Replies

7. UNIX for Dummies Questions & Answers

Truncate last <n> characters from a file

I am trying to concatenate 2 files, but before concatenation, I would like to strip off the final character from the first file. The final character is a form feed (ascii 012 / hex 0C) and there will be an unknown number of these characters in the file. It is only the very last one which I want... (1 Reply)
Discussion started by: Gwailo88
1 Replies

8. Shell Programming and Scripting

Truncate File contain

I have one file which first line is blank and second line has some data. $cat filename output: 30-MAY-07 I want to store 30-MAY-07 value in one variable. for that I wrote var="`head -2 filename`" It will give that result but I want to truncate the first line which is blank. plz help. (2 Replies)
Discussion started by: rinku
2 Replies

9. Shell Programming and Scripting

how to truncate a large (8 GB) file

Hello, I need to truncate a large file without deleting and touching it again. i tried the below commands but no use because of the huge file size cat <<! > errors and echo > errors Could someone please help. Thanks, Sateesh (1 Reply)
Discussion started by: kotasateesh
1 Replies

Featured Tech Videos